Stencil sheet



UNITED STATES PATENT OFFICE SHINJ'IRO HORII, OF TOKYO, JAPAN STENCIL SHEET No Drawing. ,Application filed July 26,

My invention relates to improvements in stencil sheets for use in duplicating manuscript and typewritten documents, drawings and the like, consisting of a sheet of fibrous material having a coating which is impermeable to ink and can be stencilized by the pressure of a writing stylus or the impact of the type of a writing machine.

It has previously been proposed to produce such a stencil sheet of fibrous base coated with a coating material including a cellulose ester, such as cellulose acetate or nitrate, and a tempering agent, such as castor oil, oleic acid or a heavy petroleum oil.

It has furthermore been proposed to produce a stencil sheet of fibrous base coated with a coating material including esters of poly saccharides and a tempering-agent such as. naphthenic acid glycerides, chlorinated a naphthalene, oleic alcohol or squalene.

The stencil sheet according to the present invention comprises a fibrous base coated with a coating material consisting of a solution of esters of polysaccharides, in a volatile solvent, in combination with naphthenic acid glycerides and a heavy hydrocarbon oil free from solid parafiine.

The hydrocarbon oil preferably employed in the present invention is a heavy viscous mineral oil which is sold widely under a variety of names, i. e., paraffinum liquidum, liquid petroleum, paraffine oil and many other special trade name r The novel feature of the present invention comprises the joint use of naphthenic acid glycerides and a heavy hydrocarbon oil. The mixture of naphthenic acid glycerides andra heavy hydrocarbon oil remains limpid even at low temperatures and its viscosity is much less affected by variations of temperature than in the case where either of them is used separately. With the use of such a mixture as a tempering agent, the stencil sheet is very dry to the touch and is remarkably soft as A 5 compared with a stencil sheet produced by the use of either fatty oils or na hthenic acid glycerides. And, moreover, t e coating is stronge'r'and more durable than in the case of hydrocarbon oils now used. The coating acding to the present invention, comprising 1928. Serial No. 295,617.

a homogeneous mixture of esters of polysaccharides, naphthenic acid glycerides and a heavy hydrocarbon oil, is stable for a long period of time without any risk of becoming rancid or sticky while being kept, as is the case when other oils, e. g. castor oil, are used either alone or in admixture with a hydrocarbon oil. Squalene is an unsaturated hydrocarbon oil and, therefore, the joint result of naphthenic acid glycerides and squalene difi'ers considerably from that of naphthenic acid glycerides and hydrocarbon oil. The principal difference is that the stencil sheet made in accordance with the present invention is stronger and more durable than where squalene is used in association with cellulose esters and other ingredients. Also, squalene is not obtained abundantly in commerce.

In the practice of this invention, a sheet of fibrous base, such as Japanese yoshino paper, is coated or impregnated with a coating material prepared by dissolving esters of polysaccharides, such as starch acetate, starch palmitate, mannan acetate, cellulose acetate, cellulose nitrate or a mixture of them in any suitable solvents, such as acetone, ether, ethyl alcohol, ethylacetate, butyl alcohol, amyl acetate, benzine, benzol, toluol or a mixture of them, and then mixing therewith naphthenic acid glycerides, together with a heavy hydrocarbon oil preferably having a specific gravity of 25 30 B. If desired, a quantity of other tempering agent, such as fatty acids, fatty oils, fats, waxes, solid hydrocarbons and ethyl or butyl phthalate, may be added to the above coating material.

The proportions of the ingredients of the coating composition may vary according to several circumstances. The following is an example:

Parts by I weight Cellulose nitrate 10 cetone; 2O Ethyl alcohol 20 Ethyl acetate 20 Amyl acetate 30 Benzol 30 Napththenic acid glycerides 15' Parafline oil at 30 B 15 The term esters of polysaccharides is intended to include not only one of definite esters of polysaccharides, but also a mixture of them.

5 What I claim is:

1. A stencil sheet, comprising a base of fibrous material and a coating composed of a mixture of esters of polysaccharides, naphthenic acid glycerides and a heavy hydrocarbon oil.

2. A stencil sheet, comprising a base of fibrous material and a coating composed of a mixture of esters of polysaccharides, naphthenic acid glycerides, a heavy hydrocarbon oil, and a tempering agent.

In testimony whereof I afiix my si ature.

SHINJIRO H R11. 

